Reversible trip blade snow plow



Jan. 1, 1957 a. w. KENYON REVERSIBLE TRIP BLADE SNOW PLOW 6 Sheets-Sheet 1 Filed Aug. 28. 1951 HTTU/P/VEY G. w. KENYONY 2,775,830

REVERSIBLE TRIP BLADE SNOW PLOW Jan. 1, 1957 Filed Aug. 28; 1951 6 Sheets-Sheet 2 BYM/M ATTORNEY Jan. 1, 1957 e. w. KENYON REVERSIBLE TRIP BLADE SNOW PLOW 6 Sheets-Sheet 3 Filed Aug. 28, 1951 INVENTOR ear '0 iii/Yangon BY ,M/

ATTORNEY Jan. 1, 1957 G. w. KENYON REVERSIBLE TRIP BLADE SNOW PLOW 6 Sheets-Sheet 4 Filed Aug. 28, 1951 INVENTOR 6%! iifi'zn BY yam ATTORNEY Jan. 1, 1957 G. w. KENYON 2,775,830

REVERSIBLE VTRIP BLADE snow PLOW Filed Aug. 28. 1951 I 6 Sheets-Sheet 5 INVENTOR [fear 6 iZ Fengmz BY ATTORNEY Jan. 1, 1957 e. w. KENYON REVERSIBLE TRIP BLADE SNOW PLOW 6 Sheets-Sheet 6 Filed Aug. 28, 1951 v 1214 1315 131a INVENTOR.

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United States Patent REVERSIBLE TRIP BLADE snow PLOW George W. Kenyon, Clayton, N. Y., assignor to Frink Silo-Flows, Iuc., Clayton, N. Y., a corporation of New York Application August; 28,1951, Serial No. 243,971

13 CIai'ms. (CI, 37-42) This invention relates to snow plow structures, and more particularly to certain structures for mounting and operatively stabilizing snow plow blades or moldboards from the front of a. motive vehicle.

It is an object of the invention to provide snow plow stabilizing means which permit ready adjustment of the angle at which the moldboard is disposed in respect to the surface over which it is being operated.

It is a further object of the invention to provide mount i'ng means for snow plow blades or moldboards which tend to eliminate the shock of impact on the mounting structure.

It is a further object of the invention to provide in a snow plow blade or moldboard mounting means a trip linkage which imparts stability to the moldboard in the normal plowing position and which exercises a restraining force that is approximately uniform throughout the tripping cycle. In this particular, the mechanism. provided also eliminates the chattering action prevalent in many snow plow structures in use at the present time.

To the end that the several objectives of the invention may be secured, there has been provided herein special stable mounting means for snow plow blade or moldboard structures that may be supported from avehicle carrying frame, thereby reducing the direct weight bearing contact of the structure with the road surface over which the plow is being operated.

Further objects and advantages of the invention will become apparent as the description thereof proceeds in connection with the drawings in which like reference numerals indicate like parts, and in which:

Fig. l is a vertical, sectional view through a snow plow blade and its supporting structure;

Fig. 2 is a horizontal view, partly in section, on line 2-2 of Fig. 1;

Fig. 3 is a plan view of the structure;

Fig. 4 is a view on line 44' of Fig. 1;

Fig. 5 is a detail, sectional view on line 5--5 of Fig. 1;

Fig. 6 is a fragmentary view'showing certain details of a clamp structure embodied in the supporting mecha-' nism;

Fig. 7 is a view on line 77 of Fig. 6;

Fig. 8 is a view on line 8-8 of Fig. 6;

Fig. 9 is a perspective view of the semi-conical structure or shell forming an important element of the combination; and i Fig. 10 is a sectional view generally on line 10-10 of Fig. 9.

The snow plow blade or moldboard 10 herein may be of conventional structure. The moldboard illustrated in the drawings includes a renewable cutting edge 12, a cutting edge reinforcement 14 and a pair of wear shoes 16, one of which is located adjacent each of the respective ends of the moldboard. The rear of the moldboard has provided thereon a plurality of upstanding reinforcing ribs 18, which not only serve to impart additional strength to the moldboard structure, but also provide Patented Jan. 1, 1957 2 means by which the moldboard is mounted on a drive frame structure.

The moldboard supporting structure includes a drive frame 20 which by reference to Fig. 2' of the drawings is seen to constitute a generally triangular structure composed of a base 22, and a pair of rearwardly converging brace members 24 and 26 which meet at the apex of the triangular structure and support thereon a universal member 28. Additional bracing structures 30 are disposed between the inner ends of the braces 24 and 2'6 and the base member 22. The several elements constituting the drive frame 20 are preferably of sufficiently heavy angle iron stock to provide the necessary strength, and these several elements are preferably welded to constitute a unitary structure.

Extending upwardly from, and at a point substantially midway of the length of the ends of the drive frame base member 22 is a guide structure 32, which is adapted to receive a swivel block 131a carried by a supporting structure which is to be described in detail at a later point herein. The guide structure comprises a pair of parallel, spaced uprights 34 and 36 which are preferably welded to the drive frame base member 22. Within the members 34 and 36 are apair of contact strips 38 and 40. The strip 38 is carried on the inner face of the upright 34 and the strip 40 is carried on the inner face of the upright 36. The upper ends of the guideway uprights 34 and 36 constitute attaching means for a carrying yoke 42, as well as means for operafively supporting one end of a trip link 44.

The carrying yoke 42 constitutes a generally inverted U-shaped. structure, asbest seen in Fig. 4 of the drawings, and this yoke is pivoted at its ends on a pivot pin 46. The yoke constitutes attaching means for a nose lift chain 48. The rearwardly extending ribs 18 carried by the rear surface of the moldboard 10 provide means by which the. moldboard is mounted on the drive frame 20. Figs. 4 and 5 of the drawings will best illustrate the manner in which the moldboard is mounted on the drive frame. By reference to Fig. 4 it will be seen, that three of the ribs 18 provide at their lower ends a pair of spaced, mounting walls 18a and 18b.

The base 22 of the drive frame 20 has three sockets spaced along the length thereof for receiving in each thereof a spring-loaded moldboard mounting cylinder 50. Each mounting cylinder includes a mounting pin 52 which has a free end 56 adapted to extend through the base 54 of the cylinder 50. The forward end of the pin 52 has an enlarged head 58 which adapts the pin for reciprocating movement within the cylinder 50. Disposed between the inner face of the enlarged head 58 and the inner face of the cylinder end wall 54 is a compression spring 60, which is preloaded and tends to project the mounting pin 52 forwardly in the cylinder 50. The spring 60 will permit the moldboard 10 to yield against obstructions in the roadway during use.

The forwardly projecting end 62 of the pin 52 is apertured to receive a mounting pin 64 when the end 62 of the pin 52 is disposed between the mounting ears lba and 18b of the rib structures 18. In this manner the moldboard 10 is mounted for tilting movement about the several pins 64, and by virtue of such mounting, tripping of the blade isprovided for under the control of a tripmechanism which is now to be described in greater detail.

In order to permit the blade to trip upon meeting obstacles in the roadway, there has been provided the trip link 44 which has heretofore been mentioned. The trip link 44 constitutes a pair of spaced link members that are rockable about a pivot pin 46. The upwardly extending ends of the trip link members carry a trip link pin 66 on which is supported one endof a moldboard brace 68, the brace being adapted to rock on the pin 66 during moldboard tripping action. The moldboard brace 68 extends forwardly where it is secured to a pair of adjacent moldboard ribs 18 by means of a moldboard brace pin 70.

The trip link 44 is connected to a trip spring mechanism 72 by means of a trip link pin 74. The pin 74 is carried by the spaced trip link members at a point disposed upwardly somewhat more than half the length of the link. More specifically, the pin 74 connects a shaft 76 constituting part of the trip spring structure and the trip link 44. The trip spring structure 72 is comprised of an elongated U-shaped frame member 73, the bight of which is fixed near the apex of the drive frame 20 by means of a pin 80 which is supported by a pair of spaced, parallel upstanding ears 82 welded to the drive frame. The forward end of the U-shaped frame 78 mounts a spring abutment member 84. The abutment member 84 includes a flange 86 through which the free ends of the U-shaped frame member 78 extend and against which bear retaining nuts 88, the retaining nuts being threaded onto the ends of the U-shaped frame. At the axis of the flange 86 is a sleeve 90 which is adapted to guide the shaft 76 so that it may reciprocate in the sleeve 90 without substantial binding during the operation thereof. The sleeve 90 also limits trip spring deflection to a safe dimension. Fixed to the outer end of the spring rod 76 is a collar 77 which is adapted to engage the outer face of the abutment member 84.

Carried by the inner end of the shaft 76 is a second abutment flange 92. The shaft 76 extends through the abutment 92 at its axis, and the two are loosely coupled together by means of a nut 94 which is screwed to the free end of the shaft 76. A pair of stop members 96 and 98, fixed to the legs of the U-shaped member 78, limit inward movement of the abutment member 92. As in the case of the abutment members 84, the inner abutment member 92 includes a flange 100 by which one end of the trip springs are supported. The trip spring mechanism is retained in its normal operative position as shown in Fig. 1 of the drawings by means of springs 102 and 104, which are positioned under compression between the flanges 86 and 100 of the respective abutment members 84 and 92. When the moldboard 10, and particularly the cutting edge thereof, encounters an obstacle in the roadway, the moldboard will be rocked in a clockwise direction about the mounting pins 64 and the moldboard brace 68 will tend to rock the trip link 44 about its pivot pin 46 and against the tension of the springs 102 and 104. When the cutting edge of the moldboard is free of the encountered obstacle, the trip spring mechanism through the associated linkage will return the moldboard to its normal operative position.

When the blade 12 encounters an obstruction in the roadway which is sufficient to cause the moldboard to trip in a clockwise direction about the pivot pins 64, such tripping action through the moldboard brace 68 and the trip link 44 will act upon the shaft 76 and compress the springs 102 and 104 by sliding the abutment plate 92 up along the legs of U-shaped member 78. As the moldboard returns to normal position, the collar 77 which is fixed to the Shaft 76 engages the abutment member 84. Consequently any overtravel due to inertia of the moldboard and linkage will cause the springs 102 and 104 to be recompressed against the abutment plate 92 which in turn bears against the steps 96 and 98. The shaft 76 is free to slide through the abutment plate 92 while the abutment member 84 slides down the legs of U-shaped member 78 and in so doing cushions the shock of the returning moldboard. Upon contact with any unusual obstruction in the roadway, the force of impact is largely absorbed by means of the spring-loaded moldboard mounting devices as previously described in connection with Fig. of the drawings.

In the normal use of the snow plow, the cutting edge of the moldboard is inclined rearwardly at ten to fifteen degrees from the vertical. For normal snow plowing operations, as in the case of new fallen snow for example, the plow operates best when the cutting edge of the moldboard is rearwardly inclined. However, under certain conditions, as for example when it is necessary to perform substantial cutting operations as in the plowing of frozen ruts or ice in roadways, it is desirable that a greater resistance be afforded to the tripping action of the blade. For this purpose, the trip link 44 has a second position 106 to which the moldboard brace 68 may be connected. When the moldboard brace 68 is connected to the trip link 44 by using the connecting aperture 106, the moldboard is tilted forward to the scraping position and at the same time the change decreases the leverage of the brace 68 on the link 44 about its hinge pin 46. The resistance to the tripping of the moldboard is increased and thus a greater cutting effect is secured from the cutting edge 12. Such cutting operations are usually performed at a lower speed than the mere clearing of roadways of new fallen snow which offers little positive resistance to the progress of the equipment.

in order to impart the necessary stability to the moldboard and the drive frame for the suspension of the moldboard during operation, there has been provided herein a structure which for purpose of illustration is shown in Figs. 9 and 10 of the drawings as a semi-conical stabilizing shell structure 108. For the purpose of this description the stabilizing shell will be referred to as an arcuate shell because an arcuate rim constitutes its most important specific element. The shell 108 is supported from a supporting or moldboard stabilizing frame 110, as best shown in Figs. 1 and 3 of the drawings. For purpose of illustration the supporting or moldboard stabilizing frame is depicted herein as being generally A-shaped. In the form chosen for illustration, moldboard stabilizing frame 110 is comprised of a base 112 and a pair of forwardly converging braces 114 and 116 having horizontal webs. The apex of the horizontal webs of braces 114 and 116 provides a flange 118 to which the apex of the shell structure 108 is attached. The base 112 of the moldboard stabilizing frame 110 provides a clamping seat and guiding structure for the arcuate rim 124 of the shell structure 108. This structure is illustrated in Figs. 1, 6, 7 and 8 of the drawings. It will appear that the base 112 of the moldboard stabilizing frame includes an inverted channel portion 112a from which depends an abutment plate 120 against which the rim 124 of the shell is adapted to bear. An overhanging portion 122 of the inverted channel 112a limits the upward movement of the semi-circle rim.

As best shown in Fig. 9 the shell 108 at its base terminates in the arcuate rim 124 which is adapted to seat in a guide and clamping structure of the moldboard stabilizing frame 110, and the apex thereof has a socket 126 by means of which it may be rotatably supported from the flange 118 of the moldboard stabilizing frame. A hearing bolt 12S serves as a pivot for the shell 108. Suitable reinforcing structures 130, 132, 132a are provided to impart strength to the shell as may be required.

The relation between the drive frame 20 and the shell 108 is established by means of a socket 131 formed at the base of the shell into which the universal 23 of the drive frame is fitted. Separation of the universal and the socket 131 is prevented by means of fastening member 28a threaded to a part of the universal 28 that extends through an aperture in the end wall of the socket 131. The relationship is further established by means of a swivel block 1311; carried at the forward side of the shell 108. The swivel block 131a is adapted for limited movement in a generally vertical direction in the guide 32 of the drive frame. It will appear, therefore, that the transverse position of the moldboard is conaarsgs'so trailed by positionof the shell 108 Because ofthe relation of the swivel'blo'ck 131a aniab the 'guide structure 32, but that undulating movement of the moldboard: in relation to the shell 108 is nevertheless permitted during operation of the device by viitueof the relationship of the two elements as just described The swivel block 1 31a (see Figs. 9'an'd has a generally rectangular head which is adapate'd for vertical movement in the guide structure 32; of thedrive frame (see Figs. 2 and 4-). The rectangular head of the swivel block 131a is on the outer end of a shaft 1231b which is carried for rocking movement in a bearing block 1310 welded to" the bottom of the rei'rifor'cin'g structure 1320. The shaft 1315 is maintained in the bearing block 131a by means of a retaining p'in 1 31d.

The shell structure 108' isopen at its front face to permit operation of the moldboard brace 68 therethrou'gh, and there is provided therein an aperture 133" near the apex thereof for acc'onimodat'i'n'g the nose lift chain 48 The moldboard stabilizing frame 11 0" and particularly the members 114* and 116 thereof have welded thereto a pair of ears 1'34 and 1-3'6, by means of which the same is supported for rocking movement about pivot pins-138a provided in a convehtional vehicle attached push frame 133, hired to the front of the motive vehicle. The operating position" of the moldboard stabilizing frame and the shell is maintained by a air ofsupporting chains I 40 extending betwee'nfthe webs 114a and 116a of the moldboard stabilizing frame and the fixed push frame 138. The nose lift chain 48i's under the controlof a hydraulic lift device 142 which is adapted to operate a lifting strut 144 to which the nose chain 48 is attached.

It will be seen, therefore", that the supporting chains 149 support the moldboard stabilizing frame and the shell in operating position. In thisregard it is to" be noted that the supporting c'hains 140" are used instead of caster assemblies common in prior devices of this kind. The lift chain 48 is for the sole purpose of lifting the moldboard free of the road surface while transportingthe plow from one scene of operation to another. During actual use of the mechanism, the lift chain- 48 is left slack so that the moldboard cutting edge is free to follow the irregularities of the road surface. The advantages of this arrangement are perhaps manifest because the conventional supporting casters,- th'eir attendant cost and trouble are eliminated; only the weight; of the moldboard assembly and a portion of the drive frame weight rides on the shoes and moldboard cutting edge as compared to the total weight of the moldboardand its supporting structure as in conventional mechanisms without casters; and of outstanding importance is the fact that there are no casters to act as a fulcrum point between the vehicle and moldboard about which the vehicle can oscillate the moldboard in passing over uneven roadways.

The transverse angular position of the moldboard 10 is adpustable so that the snow being plowed may be discharged from either the right end or the left end of the blade depending on its adjusted position. The adjustment is attained by turning the shell 108 about its pivot 128. As licreinabove pointed out, the rim 1 24 of the shell is guided in the base 112 of the moldboard stabilizing frame, and when the desired angular position of the moldboard has been attained it is locked insuch position by means of a pin 146 carried in an ear 148 fixed to and extending upwardly and forwardly of the flange 122 of the moldboard stabilizing frame. The pin 146 is adapted to enter a selected one of a series of locating holes 156 about the circumference of the shell 108 in the region just above the rim member 124.

In order to further stabilize the shell 108 in adjusted position, there is provided herein a plurality of clamps best shown in Figs. 6 through 8 by means of which the arcuate rim 124 maybe clamped against its seat in the base 112 of the moldboard stabilizing frame. A clamping structure is associated with each of the moldboard stabilizing: frame braces 11W and 116. The clamping mechanisms are identical, sothat a description of one will suffice to describe both. Figs. 6' through 8 of the drawings illustrate the clamp associated with the brace 116. The braces 1'14 and 116" are of angular, cross section, thereby providing. upstanding webs 114a and 116a which serve to support the clamp structure; Specifically, in Figs. 6 through 8, the clamp mechanism is illustrated as constituting a clamp arm 152 which is pivoted on a stud 154 that is carried by the base 112 of the moldboard stabilizing frame. Welded tothe bottom edge of the clamp arm 152 is a bifurcated plate 156 which serves to locate a spring clamping finger 158. The finger 158- has an upturned end 160 which extends through a slot in the rear end of the plate 156, where it is anchored by means of a transverse pin 1 62. The forward end 164 of the' finger 158' extends through the bifurcation of the plate 156; and it is adjustably retained in position by means of a pair of bolts 166 which straddle the finger 158 and extend through the plate 156. Between. them the bolts 166 support a half round keeper 167 which bears on the underside of the spring 158. The plate 156 and the end-164: of the spring finger 158' also serve as supporting members with sliding contact with rim 124' during angular adjustment of the shell 108-. The arrangement is such that when the arcuate rim 124 of the shell 103 is in' its seat in the base of the moldboard stabilizing frameg th'e' clamp arm 152 may be rocked about its pivot 154 in a counterclockwise direction to bring the projecting end 164 of the finger 158 into clamping contact with the arcuate rirn' 124. The clockwise rocking of. the clamp arm 152 about it's pivot pin 154 serves to release the rim 1'24.

A convenient arrangement for the manipulation of the cfamp arm 152 has been provided herein, and consists in a clamp lever 168 which is mounted for rocking movement on a pivot stud 170 carried between the upstanding web 116a and the outer end of the ear 136. Fixed to turn with the clamp lever 168 is an eccentric 172, which, when rotated to the position shown in Figs. 6 and 7, moves into operating contact with the clamp arm 152 and serves to rock the clamp arm in a counterclockwise direction to effect the clamping operation. In its clamping position the clamp arm 152 and the clamp lever 168 lie within the limits of the upstanding flange 116a. A downturned free end 174 of the clamp lever 168 abuts the horizontal web of the brace 116 and limits its clockwise movement.

The rear end of the drive frame 20 is supported by the shell-carried socket 131. Since the swivel 28 is free to rotate in the socket 131, it can be seen that the drive frame and consequently the attached moldboard may tilt in a vertical plane about the axis of the swivel 28. The forward end of the drive frame is supported by the noselift chain 48. The drive frame 20 as a whole is permitted to rise and fall about the pivot pin 28b which forms part of the swivel structure. Lateralalignment of the drive frame 20 in respect to the shell 108 and the suppcrting frame 110 is maintained by the swivel block 131a which, however, permits undulating movement, i. e. the rising and falling of the moldboard in respect to the shell 108 and the supporting frame 110 because of the vertically elongated guide structure 32 of the drive frame in which the swivel block 131a is disposed.

The rear end of the supporting frame 110 is supported from the conventional vehicle attached push frame 133, as noted heretofore, by means of the pivot pins 138a extending through the supporting frame webs 134 and 136 and forwardly extending ears of the push frame. The supporting chains 140, therefore, limit the clockwise .movement of the supporting frame 110 and the shell 108 'about the pins 138a.

From the foregoing it will be seen that there has been provided herein mechanism for supporting the moldboard or blade of a snow plow so that it may be adjustably supported from a push frame attached to the front of a motive vehicle, and that the structure is such as to provide the necessary stability for the moldboard or blade without the necessity of providing means for substantially supporting the moldboard stabilizing frame 119 and shell 108 from the surface over which the plow is being operated. Furthermore, the improved mounting of the moldboard or blade on the drive frame and its control by the trip spring mechanism renders the blade stable in operation, and this stability is practically insured by the use of the shell, the position of which controls the transverse, angular adjustment of the moldboard or blade. The positive holding means for the shell comprising the locating pin 146 and the associated clamping mechanism assures the transverse, angular position of the moldboard or blade and holds the same in a stable, adjusted position during operation.

Particular attention is directed to the fact that the entire moldboard stabilizing structure, which includes the supporting frame and associated shell, is carried by the supporting chains 140 and that the drive frame 20 and the moldboard it? may be raised and lowered through the nose chain 48 quite independently of the stabilizing structure. This is, of course, important when the power for elevating the structure is a consideration as in cases where storage batteries are used for manipulating the equipment.

The invention has been described in connection with a single operative embodiment thereof, but it is apparent that the principle of the invention may be embodied in modified form. It is, therefore, contemplated that the practice of the invention shall be limited only by the scope of the sub-joint claims.

What is claimed is:

1. In a plow stabilizing mechanism, a supporting frame, means for attaching the same to a vehicle and supporting it therefrom, a shell structure having an arcuate rim, means for rotatably supporting said shell structure in said supporting frame, a drive frame, a connection between said drive frame and said shell structure adapted to prevent relative horizontal movement between said structure and said drive frame but allow relative vertical movement therebetween, and means including spring-loaded pins for mounting a moldboard at the front of said drive frame.

2. In a plow attachment for motor vehicles, a vehicle attached frame, a moldboard stabilizing structure, a horizontal pivot for attaching said moldboard stabilizing structure to said vehicle attached frame, a drive frame supported at one end in said stabilizing structure, a connection between said stabilizing structure and the other end of said drive frame so constructed as to prevent relative horizontal movement between said stabilizing structure and said drive frame but allow relative vertical movement therebetween, cans for mounting a moldboard at the front of said drive frame, a flexible coupling between said moldboard stabilizing structure and said vehicle attached frame for limiting downward movement of said stabilizing structure about its pivot, and an operating connect on between said drive frame and said vehicle attached frame and independent of said moldboard stabilizing structure for elevating and lowering said drive frame and moldboard,

3. In a plow attachment for motor vehicles, a vehicle attached frame, a moldboard stabilizing frame, means at the base of said moldboard stabilizing frame for attaching the same to said vehicle attached frame, a structure having an arcuate rim, means in the base of said moldboard stabilizing frame for supporting the rim of said structure, means rotatably connecting said structure to said moldboard stabilizing frame, a drive frame, a

socket in the base of said structure, a universal forming a part of said drive frame secured in said socket, a second connection between said structure and said drive frame so constructed as to prevent relative horizontal movement between said structure and said drive frame but allow relative vertical movement therebetween, means for mounting a moldboard at the front of said drive frame, a flexible coupling between said moldboard stabilizing frame and said vehicle attached frame for limiting downward movement of said moldboard stabilizing frame and said structure about the pivot of said frame, and an operating connection between said drive frame and said vehicle attached frame and independent of said moldboard stabilizing frame and structure for elevating and lowering said drive frame and moldboard.

4. In a plow attachment for motor vehicles, a moldboard stabilizing frame, means in said moldboard stabilizing frame for attaching the same to a vehicle, a shell having an arcuate rim, means in said moldboard stabilizing frame for supporting the rim of said shell, means rotatably connecting said shell to said moldboard stabilizing frame, a drive frame, a universal connection between said drive frame and said shell, a second connection between said shell and said drive frame so constructed as to prevent relative horizontal movement between said shell and said drive frame but allow relative vertical movement therebetween, means for mounting a mold board at the front of said drive frame for vertical rocking motion, a moldboard trip mechanism carried by said drive frame, and a trip lever connecting said trip mechanism and said moldboard.

5. In a plow attachment for motor vehicles, a moldboard stabilizing frame, means in said moldboard stabilizing frame for attaching the same to a vehicle, a structure having an arcuate rim, means in said moldboard stabilizing frame for supporting the rim of said structure, means rotatably connecting said structure to said moldboard stabilizing frame, a drive frame, a first connection between said drive frame and said structure, a second connection between said structure and said drive frame so constructed as to prevent relative horizontal movement between said structure and said drive frame but allow relative vertical movement therebetween, and a plurality of spring-pressed pins for mounting a moldboard at the front of said drive frame.

6. In a plow attachment for motor vehicles, a moldboard stabilizing frame, means in said moldboard stabilizing frame for attaching the same to a vehicle, a structure having an arcuate rim, means in said moldboard stabilizing frame for supporting the rim of said structure, means rotatably connecting said structure to said moldboard stabilizing frame, a drive frame, a socket in the base of said structure, a universal forming a part of said drive frame secured in said socket, a vertical guide channel in said drive frame, an arbored guide mounted on said structure and extending into said channel, thereby preventing relative horizontal movement between said structure and said drive frame but allowing relative vertical and horizontal rocking movement therebetween, and means for mounting a moldboard at the front of said drive frame.

7. In a plow attachment for motor vehicles, a moldboard stabilizing frame, means in said moldboard stabilizing frame for attaching the same to a vehicle, a structure having an arcuate rim, means in said moldboard stabilizing frame for supporting the rim of said structure, means rotatably connecting said structure to said moldboard stabilizing frame, a drive frame, a universal connection between said drive frame and said structure, a second connection between said structure and said drive frame so constructed as to prevent relative horizontal movement be ween said structure and said drive frame but allow relative vertical movement therebetween, a plurality of structure locating apertures spaced along the base of said structure, a pin carried by said moldboard stabilizing 9 frame adapted to enter a selected aperture to fix the rotational position of said structure, and means for mounting a moldboard at the front of said drive frame.

8. In a plow attachment for motor vehicles, a moldboard stabilizing frame, means at the base of said moldboard stabilizing frame for attaching the same to a vehicle, a structure having an arcuate rim, means in the base of said moldboard stabilizing frame for supporting the rim of said structure, means rotatably connecting said structure to said moldboard stabilizing frame, a drive frame, a socket in the base of said structure, a universal forming a part of said drive frame secured in said socket, a second connection between said structure and said drive frame so constructed as to prevent relative horizontal movement between said structure and said drive frame but allow relative vertical movement therebetween, a seat in said moldboard stabilizing frame, clamp means carried by said moldboard stabilizing frame adapted to clamp the rim of said structure against said seat, and means for mounting a moldboard at the front of said drive frame.

9. In a plow attachment for motor vehicles, a moldboard stabilizing frame, means in said moldboard stabilizing frame for attaching the same to a vehicle, a structure having an arcuate rim, means in said moldboard stabilizing frame for supporting the rim of said structure, means rotatably connecting said structure to said moldboard stabilizing frame, a drive frame, 'a socket in said structure, a universal forming a part of said drive frame secured in said socket, a second connection between said structure and said drive frame so constructed as to prevent relative horizontal movement between said structure and said drive frame but allow relative vertical movement therebetween, means for mounting a moldboard at the front of said drive frame for horizontal rocking motion, a spring controlled moldboard trip mechanism carried by said drive frame, a trip link under control of said mechanism, a trip lever extending between said link and said moldboard, and means for changing the point of connection between said link and said lever to alter the trip resistance of said moldboard.

10. In a plow attachment for motor vehicles, a moldboard stabilizing frame, means in said moldboard stabilizing frame for attaching the same to a vehicle, a structure having an arcuate rim, means in said moldboard stabilizing frame for supporting the rim of said structure, means rotatably connecting said structure to said moldboard stabilizing frame, a drive frame, a socket in said structure, a universal forming a part of said drive frame secured in said socket, a second connection between said structure and said drive frame so constructed as to prevent relative horizontal movement between said structure and said drive frame but allow relative vertical movement therebetween, a plurality of structure locating apertures spaced along the base of said structure, a pin carried by said moldboard stabilizing frame adapted to enter a selected one of said apertures to fix the rotational position of said structure, a seat in said moldboard stabilizing frame, clamp means carried by said moldboard stabilizing frame to clamp the base of said structure against said seat, and means for mounting a moldboard at the front of said drive frame.

11. In a plow attachment for motor vehicles, a supporting frame, means in said supporting frame for attaching the same to a vehicle, a structure having an arcuate rim, means in said supporting frame for supporting the arcuate rim of said structure, means rotatably connecting said structure to said supporting frame, a drive frame, a universal connection between said drive frame and said structure, a vertical guide channel in said drive frame, a guide block mounted on said structure and extending into said channel, thereby preventing relative horizontal movement between said structure and said drive frame but allowing relative vertical movement therebetween, means for' adjusting the rotational position of said structure, means for fixing said structure in a selected rotational position of adjustment, and means for mounting a moldboard at the front of said drive frame.

12. In a plow attachment for motor vehicles, a supporting frame, means in said supporting frame for attaching the same to a vehicle, a structure having an arcuate rim, means in said supporting frame for supporting the arcuate rim of said structure, means rotatably connecting said structure to said supporting frame, a drive frame, a socket in the base of said structure, a universal forming a part of said drive frame secured in said socket, a second connection between said structure and said drive frame so constructed as to prevent relative horizontal movement between said structure and said drive frame but allow relative vertical movement therebetween, a plurality of springpressed pins for mounting a moldboard at the front of said drive frame for horizontal rocking motion, a spring controlled moldboard trip mechanism carried by said frame, and a trip lever connecting said trip mechanism and said moldboard.

13. In a plow attachment for motor vehicles, a supporting frame, means in said support-ing frame for attaching the same to a vehicle, a structure having an arcuate rim, means in said supporting frame for supporting the arcuate rim of said structure, means rotatably connecting said structure to said supporting frame, a drive frame, a socket in said structure, a universal forming a part of said drive frame secured in said socket, a vertical guide channel in said drive frame, a guide block mounted on said structure and extending into said channel, means for adjusting the rotational position of said structure, a pin for fixing said structure in adjusted rotational position, means carried by said supporting frame for clamping said structure to said supporting frame, and means for mounting a moldboard at the front of said drive frame.

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